void mainImage(out vec4 fragColor, in vec2 fragCoord){
    vec3 color1 = vec3(1., 0., 1.);
    vec3 color2 = vec3(1., 1., 0.);
    vec3 color3 = vec3(0., 0., 1.);
    vec3 color4 = vec3(1., 0., 0.);

    if(fragCoord.x < iResolution.x * 0.25){
        fragColor = vec4(color1, 1.);
    }else if(fragCoord.x < iResolution.x * .5){
        fragColor = vec4(color2, 1.);
    }else if(fragCoord.x < iResolution.x * 0.75){
        fragColor = vec4(color3, 1.);
    }else{
        fragColor = vec4(color4, 1.);
    }
}